Mitsubishi Electric FR-D720S SC EC Instruction Manual page 94

Precautions for use of the inverter
Output terminal function assignment
When using various signals, assign functions to Pr. 190, Pr. 192 and Pr. 197 "output terminal
function selection" referring to the table below
Output Signal
ALM
RY
RUN
Y12
Tab. 4-2: Setting in positive and negative logic
NOTE
Changing the terminal assignment using Pr. 190, Pr. 192 and Pr. 197 may affect the other
functions. Make setting after confirming the function of each terminal.
Backup method outside the inverter
Even if the interlock is provided by the inverter status signal, enough failsafe is not ensured de-
pending on the failure status of the inverter itself. For example, when the inverter CPU fails, even
if the interlock is provided using the inverter fault signal, start signal and RUN signal, there is a
case where a fault signal is not output and RUN signal is kept output even if an inverter fault oc-
curs.
Provide a speed detector to detect the motor speed and current detector to detect the motor cur-
rent and consider the backup system such as checking up as below according to the level of im-
portance of the system. Check the motor running and motor current while the start signal is input
to the inverter by comparing the start signal to the inverter and detected speed of the speed de-
tector or detected current of the current detector. Note that the motor current runs as the motor
is running for the period until the motor stops since the inverter starts decelerating even if the
start signal turns off. For the logic check, configure a sequence considering the inverter decel-
eration time. In addition, it is recommended to check the three-phase current when using the cur-
rent detector.
Fig. 4-4: Backup method outside the inverter
Check if there is no gap between the actual speed and commanded speed by comparing the in-
verter speed command and detected speed of the speed detector.
4 - 6
System failure
190, 192 and 197 Setting
Positive Logic
99
11
0
12
Controller
Inverter
air volume, etc.)
To the alarm detection sensor
Negative Logic
199
111
100
112
Sensor
(speed,
temperature,
Operation
I001879E